Oil burner and fuel cutoff system



May 29, .1951 H. E. EARL OIL BURNER AND FUEL CUTOF'F SYSTEM 2Sheets-Sheet 1 INVENTOR.

,77'7IFNE' Filed Jan. 17, 1948 May'29, 1951 H. E. EARL OIL BURNER ANDFUEL CUTOFF SYSTEM Filed Jan. 17, 1948 ZSheets-Shec 2 iii;

A A Q S X m1 M M FM, m N M 2 d J m 5 Patented May 29, 1951 UNITED STATESPATENT OFFICE OIL BURNER AND FUEL CUTOFF SYSTEM Howard E. Earl,Bloomington, 111., assignor to Eureka Williams Corporation, Bloomington,111., a corporation of Michigan Application January 17, 1948, Serial No.2,881

' is formed by mixing together a small quantity of air and fuel atsubstantially equal low pressures and then igniting and burning thismixture beyond a burner nozzle through which the main air supply for theburner system also is discharged.

Some of the objects of the invention are i provide:

An oil burner system of the low pressure type @in which the oil supplyto the mixing nozzle .mains automatically cut off until the mechanics.

elements of the system are operating at a prr determined or normaloperating speed and then supplying fuel to the nozzle during the norms.operation of the burner.

An oil burner system in which the oil Suppl to the mixing nozzle of theburner is cut off whey themechanical elements of the burner ceaseoperate under normal operating conditions and. start to slow down at theend of a burner operating cycle.

An oil burner employing a pumping unit 2 one of the mechanical elementsthereof and in which pumping unit the oil pumping mechanism is renderedinoperative below a predetermineor normal operating speed for suchmechanism.

An oil burner system employing a centrifugally actuated switch, asolenoid actuated valve, and a fuel pumping mechanism, all of whichoperate in such manner as to cut off the fuel supply to the burnernozzle at the beginning and at the end of an operational cycle when themechanical elements of the burner system are operating below apredetermined operating speed.

Other and further objects of the invention will be apparent by referenceto the accompanying drawings of which there are two sheets, which by wayof illustration, show a preferred embodiment and the principles thereofand what I now consider to be the best mode in which I have contemplatedapplying these principles. Othe embodiments of the invention embodyingthe same or equivalent principles may be used and structural changes maybe made as desired by those skilled in the art without departing fromthe present invention and the purview of the appended claims. I alsocontemplate that of the several difierent features of my invention,certain ones thereof may be advantageously employed in some applicationsseparate and apart from the remainder of the features.

Referring particularly to the drawings:

Fig. 1 illustrates an elevational view of an burner system embracing theprinciples of the: invention.

Figs. 2 and 3 represent a. schematic view of the principal elements ofthe charge forming and fuel burning elements of the oil burner systemillustrated by Fig 1.

Fig. 4 is a fragmentary transverse sectional view through the fuelmetering pump embraced in the fuel pumping mechanism illustrated by Fig.2. Fig. 4 is taken in the plane of line 4-4 on Fig. 2 looking in thedirection of the arrows.

Referring particularly to Fig. 1, the numeral Ill indicates generally anoil burner apparatus or system adapted to be supported upon a frame ii.Extending upwardly from the central portion of the frame II is a housingI2 to which is attached on opposite sides of the top thereof a motor l3and a pumping unit 14. The central portion of the aforesaid upper partof the housing l2 provides a fan housing [5 in which is located acentrifugal fan or blower H. The 1110- tor l3 drives the fan I! througha driving shaft 18 and which shaft in turn drives the shaft id of thepumping unit [4 through a coupling 2|. A transformer 22 for theelectrical apparatus of the system is secured to one side of the lowerpart of the housing l2, while the oil burner control mechanism 23 issecured to the opposite side of the lower portion of the housing l2.

The main air supply for the oil burner system Ill is supplied by the fanI"! through a main air supply conduit 24 which terminates in a sec--ondary burner nozzle 25 adapted to be disposed in the fire box orcombustion chamber of a heating system, not shown, but with which theoil burner apparatus referred to is adapted to be employed. Burnernozzle 26 is provided with spirally disposed internally projecting vanes27 for rotating or whirling the main air supply received from theconduit 24. Immediately within the end of the burner nozzle 26 is a lowpressure air and oil mixing nozzle 28 which is adapted to supply a richmixture of oil and air to the central portion of the burner nozzle 26 tobe ignited and burned with the main air supply received from the conduit24. The mixing nozzle 28 comprises a discharge orifice 29 communicatingwith a plurality of mixing passages 3| which in turn communicate with anannular air supply passage 32 formed internally of the mixing nozzle 28.Within the air supply passage 32 is formed a duel supply chamber 33which com municates with the mixing passages 3| through angularlydisposed fuel supply passages 34. EX- tending coaxially with respect tothe air supply conduit 24 is a pair of air and fuel delivery conduits 36and 3'1 respectively within which are provided air and fuel deliveringpassages 38 and 39, also respectively. The passage 33 communicates withthe air supply chamber 32, while the passage 39 communicates with thefuel supply chamber 33.

just back of the mixing nozzle 28 is an ad'ustable bracket ll in whichignitor fo burner apparatus is secured. The ignitor s2 is provided withelectrodes id adjacent the discharge orifice 2s and within the burnernozzle 26. The electrodes 44 are adapted to provide an electrical sparkat the beginning of each cycle of operations of the oil burner ap;igniting the combustible mixture formed within the burner nozzle 26 bythe fuel and air mixture discharged by the orifice 29 and the main airsupply delivered to the burner nozzle by the conduit 24. a

The pumping unit It comprises a casing it within which is contained anair supply pur l 46, a fuel supplypump island a fuel meterl pump 48. Thepumps 46; 41-, and ii: are all mounted within the casing 16 in suchmanner as to be driven by the pumping unit shaft I9. The air pump 46 isformed in an air pump housing 49 secured to one side of a central web orsupport portion SI of the casing it, while the fuel pump 41 and fuelmetering pump 48 are disposed with in a housing 52 secured to theopposite side of thesup-port The shaft I9 is mounted within the pumphousings t9 and 52 upon self-aligning bearings 53 and 54, and betweenthe bearings there is provided a fluid seal 55 having a movable member5-? secured to the shaft ii) and a stationary member 58 secured by adiaphragm 59 to one side of the support 5i. The support 5| and the pumphousing 52 are provided with a centrally disposed fuel chamber 6! inwhich the seal 58 and the bearing 54 are located.

The air pump 4% is provided with an inlet port 62 communicating with aninlet passage t3 which supplies air to the pump from the annular spacewithin the casing. I5 surrounding the housings 49 and 52. A dischargeport (is is provided in the housing' iii on the discharge side of thepump lii. The discharge port coinmunicates with the discharge passage 8Bwhich communicates with the air delivery passage 38 for supplying air tothe nozzle 22% through an air supply conduit '37. The passage 56 is alsoprovided with a by-pass 5'8 controlled by a needle valve I39 which isaccessible from the exterior of the casing I6. The opposite end of the-pass 88 is in open communication with the annular space within thecasing lithrough a port indicated at In.

The fuel pump 41 has an inlet port 5 I communicating with an inletpassage 72 supplied with fuel from a fuel supply chamber 73 which inturn communicates with the fuel supply tank, not shown, through aconduit The fuel discharge for the pump ll is provided by a dischargeport which communicates with the chamber 6 through a discharge passageii. A by-pass it from the chamber permits fuel to return to the fueltank through a by-pass valve '59 and a fuel return conduit Si, alsoconimunicating with the tank not shown.

Instead of eniployingthe conduit 8!, the opening in the casing I6 inwhich the conduit is threaded may be closed by a plug and in such eventthe by-pass 18' may communicate with the fuel supply chamber's'iithrough an opening, not shown, but which may be formed axially withrespect to a screw 82 disposed in a threaded opening 83 formed'in t; ecasing in such manner as to communicate with the by-pass '58. Thechamber Bl also communicates through delivery passages 86 with a pumpingchamber 8? formed in the housing 52. The fuel metering pump 48 islocated within the pumping chamber 81.

In order to provide a resilient drive means for the fuel metering pump58, the shaft coupling 2I, the bearings 53 and 5a, and the pumps 46 andii are all mounted upon the shaft IS in such to permit a movement of theshaft and In order to provide means for resiliently urging the shaft iswithin the bearings 53 and ii in a direction toward the fuel meteringpump there is proviced within the chamber 6! and beyond the diaphragm 55a spring 88 which is disposed between the pumping housing l9 and thestationary member 53' of the seal 55. The spring 88, being undercompression, tends therefore to move the shaft I8 toward the fuelmetering pump 48 by reason of the fact that the seal is secured to theshaft IP, by the rotating member 5"! of the seal 56. The end of theshaft IS- terminates at the pumping chamber 8? adjacent the rotor of themetering pump .8 which is adapted to be rotated by the shaft I9 againsta wall indicated at GI formed in the housing 52 on one side of thepumping chamber 81. The rotor 89 is rotated by the shaft [9' through theenergy imparted by a ball 92 which is partly seated in openings J3 andformed in the shaft I9 and rotor so respectively. The opening 93 isformed the end of the shaft lSeccentrically with respect thereto, whilethe'opening 94. is formed in the rotor 89 concentrically with respectthereto. It will be apparent that the spring 88 tends to hold the shaftis resiliently against the ball 92 and that the ball 92 tends to holdrotor 89 resiliently against the wall Ill. The rotor 89 has a radiallydisposed cylindrical opening 96 formed therein in which is reciprocablymounted a piston iii. The opposite end of the piston 9! is resiliently m.mted upon a spring 93 in a spherical bearing member 99 which is mountedfor linear and oscillatory movement in a cylindrical opening Ilil formedin the housing 52 in parallel relation to theaxis of the shaft 9. Thecylindrical opening Iiil communicates with and provides a continuationof the pumping chamber 8'5.

The wall GI is provided with an annular pressure chamber IE2 which isformed as a groove extending within the wall and against which groovethe rotor 89 rotates. The chamber I02 communicatesthrough a passage I03with a discharge port IEM-which isalso formed in the wall e: and whichcommunicates with the cylinder 96 through a passage I06 when the pistonSi! is moving inwardly with respect to the cylinder 96. The passage I66is formed in the rotor 39 between the cylinder 96 and the Wall 9|. Aninlet port it? also is formed in the Wall 9| and within the annularpressure chamber I02 and is adapted to communicate with the passage I96when the piston 97 is moving outwardly within the cylinder The inletport I'fi'l' communicates with the pressure chamber 87' t .rough aninlet passage I38 while the-discharge port I04 communicates with thefuel delivery passage fig'through a fuel supply passage Its and a fuelsupply conduit I l I. The passages I93 and I09 are respectively connected to surge chambers I I2 and l l3 which are adap ed to dampen outvibrations in fluid pressure which may-'occurwi'thin the passages.

The fuel supply conduit" I1 I is connected intermediate the ends thereofto a valve casing H4 having an orifice I I6 controlled by a needle valvestarting winding I 24 of the motor I3. after the motor will start andwill accelerate un- III operated by the armature IIB of a solenoid II9of a solenoid actuated valve member I2 I.

When the solenoid H2 is electrically energized the armature II8 will bemoved in such manner as to open the needle valve II? with respect to theseat II6 to permit the normal flow of fluid through the fuel supplyconduit III. When the solenoid I I9 is not energized the needle valve II! will close by gravity upon its seat II6 thereby preventing the flowof fuel through the fuel supply conduit III. Mounted upon shaft [8 ofthe motor I3 is a centrifugally actuated switch I22 having a contactmember I23 adapted alternate- 1y to close an electrical circuit throughthe starting winding I24 of the motor I3 and the solenoid I I9 of thesolenoid actuated valve I2I. The contact member I23 has a two-waycontact I26 adapted alternately to engage contacts I21 and I26 for suchrespective purposes. The contact member I 23 is mounted at the endthereof opposite the contacts I26 upon a portion of the motor frame I29through which the shaft I8 pro- 'je'cts. On one side of the contactmember I23 is weights I38. The weights I38 are formed in the shape oflevers, one of the ends of each lever being adapted to move outwardly bycentrifugal force resulting from rotation of the shaft I8 intoengagement with the inner surface of the arms The opposite end of eachlever is pivotally mounted at I39 in openings formed in the periphcry ofthe ring I32. It will be apparent that the outward movement of theweights I38 resulting am the rotation of the shaft It will move the ringI32 against the compression of the spring I33, thus permitting thecontact member I23 to en age the contact I 26 with the contact I28. The

spring I33 is constructed and arranged in such manner that the contactI26 will so close upon the contact I28 when the motor I3 has reached apre I determined operating speed which preferably is just below thenormal operating speed of the motor [3. Just below such predeterminedoperating speed it will be apparent that the spring I33 will'move thering I32 and the contact member I23 in such manner as to open thecircuit through contacts I 25 and I28 and to close the circuit betweencontacts I26 and I21.

- Contact I28 is connected to one side I 4|.of a power line I42 inseries with the solenoid H3 of the solenoid actuated valve I2I byconductors in- (heated at I43. Contact I21 also is connected to the sameside I4I of the line I42 by conductors I44. Contacts I25 and the runningwinding I43 of the motor I3 are connected to the other side I41 of theline I42 by conductors I48 and I49 respectively. The running winding I46also is con nected to the side I4I of the linein parallel with startingwinding I24 by one of the conductors I44. When switch I5I controllingthe line I42 is closed prior to the starting of the motor I3, it will beapparent that an electrical circuit will be made through contacts I26and I2! for energizing the Theretil such time as the motor shaft I8 hasreached the predetermined speed previously referred to in which eventthe operation of the centrifugally actuated switch I22 Will close thecircuit through the contacts I26 and I28 thereby opening the circuitthrough the starting winding I24 and closing the circuit through thesolenoid II9 of the solenoid actuated valve I2I It will also be apparentthat upon closing the switch I5I controlling the line 42, that thestarting of the motor I3 will result in driving the air pump 46, thefuel pump 4?, and the fuel metering pump 48 at the speed of the motorshaft. However, due to the fact that the solenoid actuated valve I 2I isnot at such time energized in such manner as to open the conduit I I Ibeyond the needle valve I I6, fluid pressure in the discharge port I84,in the pressure chamber IE2, the discharge passage I232 and thedischarge conduit III will tend to increase Icetween the metering pump48 and the solenoid actuated valve I2I. Since the rotor 89 of themetering pump 48 is exposed to the fluid pressure within the pressurechamber 582 and the discharge passage I54, it will be apparent that therotor 89 will tend to be forced away from the wall 9! against thecompression of the spring 88. Since liquid fuel is relativelynon-compressible. it will also be apparent that a considerable increasein fluid pressure in the pressure chamber I92 and the discharge port I64will occur immediately upon the starting of the motor I3 and the pumps46, 47, and 48. When the fluid pressure in the pressure chamber lit?!and the discharge port 1534 has increased to a predetermined value,depending upon the calibration of the spring 88, the rotor 89 will bemoved away from the wall 9| a suflicient amount to render the meteringpump 48 inoperative for the pur pose of pumping measured quantities offuel from the inlet port I Bl to the discharge port I64. Thereafter thefluid pressure in the pressure chamber I82 and the discharge port willbe relieved along the well 9| to the pumping chamber 21 and in suchevent the fiui-dpressure in the supply conduit ii I willdecrease or inany event will not tend to increase beyond the predetermined fluidpressure previously referred to.

When the motor I3, the pump 46, the pump 4?, and the fuel metering pump48 have all reached predetermined speed just below normal operatingspeed for all of such units, the centrifugally actuated switch I 22 willoperate in such manner as to open the circuit between the contacts i26and I2! and to close the circuit through the contacts I26 and I26thereby actuating the solenoid actuated valve IZI in such manner as toopen the needle valve Ill upon the orifice I Hi to permit the flow offuel through the fuel supply conduit III. When the solenoid actuatedvalve I2! is so opened, the pressure in the discharge port I @4. and thepressure chamber IE2 will be relieved to such an extent as to permit therotor 89 to be resiliently urged by the spring 88 into operativerelation to the wall i i. Thereafter the metering pump 48 will supplymeasured quantities of fuel from the pumping chamber 8'! to the nozzle28 to be there mixed with air at approximately the same pressuredelivered by the air pump 46 to the nozzle 28.

Operation of the ignitor 42 thereupon will ignite the combustible chargeformed in the burner nozzle 26 and the burner thereafter c i e tooperate under normal operatin during the continuation of an operatingcycle for the oil burner apparatus. When the switch I! is opened at theend of such normal operating cycle for the oil burner apparatus byoperation of the control mechanism 23 the speed of the motor shaft Itwill decrease. When the speed of shaft [8 is decreased to thepredetermined operating speed previously referred to, the centrifugallyactuated switch i22 will operate to open the circuit betweencontact/5126 and I23. However, the circuit through switch lei havingalready been opened, the solenoid actuated valve l2l will again permitthe closing of the needle valve li'l upon the seat H 5 immediately uponopening of the circuit through switch NH. The resulting immediate risein pressure in the supply conduit ill will increase the fluid pressurein the pressure chamber I62 and the discharge port I84 to such an extentas to render the fuel metering pump 48 inoperative in the mannerpreviously described.

It will be apparent that while air will be sup- 13, the pump 46, thepump 4?, and the fuel metering pump 48.

While I have illustrated and described a preferred embodiment of myinvention, it is understood that this is capable of modification, and Itherefore do not wish to be limited to the precise details set forth,but desire to avail myself of such changes and alterations as fallWithin the purview of the following claims.

I claim:

1. An oil burner system comprising a burner nozzle, fuel and air pumpingmeans for supplying fuel and air to said burner nozzle, said fuelpumping means having a discharge port connected with said nozzle, meansresponsive to the speed of operation of said fuel and air pump-ing meansfor increasing the fluid pressure in said discharge port, said speedresponsive means being operative for preventing flow of fuel to saidnozzle and for increasing said fluid pressure at speeds below apredetermined operational speed for said fuel and air pumping means, andmeans responsive to a predetermined increase in said fluid pressure insaid discharge port for rendering said fuel pumping means inoperativefor supplying said fuel to said burner nozzle below said predeterminedoperational soeed for said pumping means, said speed responsive meansbeing operative for relieving the fluid pressure in said discharge portand permitting flow of fuel to said nozzle at speeds of said pumpingmeans above said predetermined operational speed thereof, said airpumping means being operative at speeds below and abovesaidpredeterinined speed for supplying a stream of secondary air pastsaid nozzle and said nozzle being operative for mixing the fuel and airsupplied thereto and discharging the resulting mixture into saidsecondary air stream.

2. An oil burner system comprising a burner nozzle, fuel and air pumpingmeans for supplying fuel and air to said burner nozzle, said fuel pumpinmeans having a discharge port connccted with said nozzle, meansresponsive to the speed of operation of said fuel and air pumping meansfor increasing the fluid pressure in said discharge port, said speedresponsive means being operative for preventing flow of fuel to saidnozzle and for increasing said fluid pressure at speeds below apredetermined opera tional speed for said fuel and air pumping means,means responsive to a predetermined increase in said fluid pressure insaid discharge port for rendering said fuel pumping means inoperativefor supplying said fuel to said burner nozzle below said predeterminedspeed for said pumping means, and said fuel pumping means having apressure chamber connected to said discharge port and exposed to saidpressure responsive means for increasing the total effective pressure ofsaid fluid upon said pressure responsive means, said speed responsivemeans being operative for relieving the fluid pressure in said dischargeport and pressure chamber and ermitting flow of fuel to said nozzle atspeeds of said pumping means above said predetermined operational speedthereof, said air pumping means being operative at speeds belowand abovesaid predetermined speed for supplying a stream of secondary air pastsaid nozzle and said nozzle being operative for mixing the fuel and airsupplied thereto and discharging the resulting mixture into saidsecondary air stream.

3. An oil burner system comprising a burner nozzle, fuel and air pumpingmeans for supplying fuel and air to said burner nozzle, said fuelpumping means having a discharge port con-- nected with said nozzle,means responsive to the speed of operation of said fuel and air pumpingmeans for increasing the fluid pressure in said discharge port, saidspeed responsive means being operative for preventing flow of fuel tosaid nozzle and for increasing said fluid pressure at speeds below apredetermined operational speed for said fuel pumping means, meansresponsive to a predetermined increase in said fluid pressure in saiddischarge port for rendering said fuel pumping means inoperative forsupplying said fuel to said burner nozzle below said predetermined speedfor said pumping means, and said fuel pumping means having an annularpressure chamber surrounding said discharge port and exposed to saidpressure responsive means for increasing the total eifective pressure ofsaid fluid upon said pressure responsive means, said speed responsivemeans being operative for relieving the fluid pressure in said dischargeport and pres-, sure chamber and permitting flow of fuel to said nozzleat speeds of said pumping means above said predetermined operationalspeed thereof, said air pumping means being operative at speeds belowand above said predetermined speed for supplying a stream of secondaryair past said nozzle and said nozzle being operative for mixing the fueland air supplied thereto and discharging the resulting mixture into saidsecondary air stream.

4. An oil burner system comprising a burner nozzle, fuel and air pumpingmeans for supplying fuel and air to said burner nozzle, said fuelpumping means having inlet and discharge ports connected with saidnozzle, means responsive to the speed of operation of said fuel and airpumping means for increasing the fluid pressure in said discharge port,said speed responsive means being operative for preventing flow of fuelto said nozzle and for increasing said fluid pressure at speeds below apredetermined operational speed for said fuel pumping means, meansresponsive to a predetermined increase in said fluid pressure in saiddischarge port for rendering said fuel pumping means inoperative forsupplying said fuel to said burner nozzle below said predetermined speedfor said pumping. means, and said fuel pumping means having an annularpressure chamber surrounding said inlet and discharge ports and exposedto said pressure responsive means for increasing the total effectivepressure of said fluid upon said pressure responsive means, said speedresponsive means being operative for relieving thefluid pressure in saiddischarge port and pressure chamber and permitting flow of fuel to saidnozzle at speeds of said pumping means above said predeterminedoperational speed thereof, said air pumping means being operative atspeeds below and above said predetermined speed for sup-plying a streamof secondary air past said nozzle and said nozzle being operative formixing the fuel and air supplied thereto and discharging the resultingmixture into said secondary air stream.

5. An oil burner system comprising a burner nozzle, fuel pumping meansfor supplying said fuel to said burner nozzle, said fuel pumping meanshaving an inlet port and a discharge port connected with said nozzle,means responsive to the speed of operation of said fuel pumping meansfor increasing the fluid pressure in said discharge port, said speedresponsive means being operative for preventing flow of fuel to saidnozzle and for increasing said fluid pressure at speeds below apredetermined, operational speed for said fuel pumping means, meansresponsive to a predetermined increase in said fluid pressure in saiddischarge port for rendering said fuel pumping means inoperative forsupplying said fuel to said burner nozzle below said predetermined speedof said pumping means, and said fuel pumping means having an annularpressure chamber surrounding said inlet and discharge ports and exposedto said pressure responsive means for increasing the total effectivepressure of said fluid upon said pressure responsive means, said speedresponsive means being operative for relieving. the fluid pressure insaid discharge port and permitting flow of fuel to said nozzle at speedsof said pumping means above said predetermined operational speedthereof.

6, An oil burner system comprising a burner nozzle, fuel pumping meansfor supplying said fuel to said burner nozzle, said fuel pumping meanshaving a discharge port connected with said nozzle, means responsive tothe speed of operation of said fuel pumping means for increasing thefluid pressure in said discharge port, said speed responsive means beingoperative for preventing flow of fuel to said nozzle and for increasingsaid fluid pressure at speeds below a predetermined operational speedfor said fuel pumping means, means responsive to a predeterminedincrease in said fluid pressure in said discharge port for renderingsaid fuel pumping means inoperative for supplying said fuel to saidburner nozzle below said predetermined speed of said pumping means, andsaid fuel pumping means having a pressure chamber surrounding saiddischarge port and exposed to said pressure responsive means forincreasing the total effective pressure of said fluid upon said pressureresponsive means, said speed responsive means being operative forrelieving the fluid pressure in said discharge port and permitting flowof fuel to said nozzle at speeds of said pumping means above saidpredetermined operational speed thereof.

'7. An oil burner system comprising a burner nozzle operative fordischarging a combustible mixture of fuel and air, a pumping unitassociated with said burner nozzle and operative for supplying saidmixture to said burner nozzle and a secondary air stream past saidnozzle into which said mixture is discharged, said pumping unitcomprising a pumping chamber having a rotor disposed therein, resilientmeans for rotating said rotor against a wall of said chamber for pumpingthe fuel mployed in said m xture to said burner nozzle, said Wall havinga discharge port therein in opposite relation to said rotor, the fluidpressure in said discharge port being opposed to said resilient means,and means responsive to the speed of said resilient means fordiscontinuing the supply of said fuel to said burner nozzle and forincreasing said fluid pressure in said discharge port, said rotor beingmovable by the fluid pressure in the discharge port said resilient meansaway from said Wall for relieving said fluid pressure intosaid pumpingchamber below a predetermined speed of operation of said resilientmeans.

8. An oil burner system comprising a burner nozzle operative fordischarging a combustible mixture of fuel and air, a pumping unitassociated with said burner nozzle and operative for supplying saidmixture to said burner nozzle and a secondary air stream past saidnozzle into which said mixture is discharged, said pumping unitcomprising a pumping chamber having a rotor disposed therein, resilientmeans for rotating said rotor against a wall of said chamber for pumpingthe fuel employed in said mixture to said burner nozzle, said wallhaving inlet and discharge ports therein in opposite relation to saidrotor, means forming an annular pressure chamber surrounding said inletand said discharge ports, said pressure chamber being in opencommunication with said discharge port and being formed between rotorand said wall, the fluid pressure in said discharge port and pressurechambers being opposed to said resilient means, and means responsive tothe speed of said resilient means for discontinuing the supply of saidfuel to said burner nozzle and for increasing said fluid pressure insaid discharge port and said pressure chamber, said rotor being movableby the fluid pressure in the discharge port and pressure chamber againstsaid resilient means away from said wall for relieving said fluidpressure into said pumping chamber below a predetermined speed ofoperation of said resilient means.

9. An oil burner system comprising a burner nozzle, means for supplyinga combustibl mixture of fuel and air to said burner nozzle, said fuelsupplying means comprising a fuel metering pump having a discharge port,means supporting said pump for movement in response to pressure, saidfuel metering pump being movable in response to the pressure of fuel insaid discharge port for rendering said pump inoperative to sup ply fuelto said nozzle, means responsive to the operation of said fuel and airsupplying means for increasing the pressure of fuel in said dischargeport below a predetermined operating speed for said fuel and airsupplying means, and means forming a pressure chamber connected to saiddischarge port and associated with said fuel metering pump foraccelerating the movement of said fuel metering pump in response to saidfuel pressure.

10. An oil burner system comprising a burner nozzle, means for supplyinga combustible mix ture of fuel and air to said burner nozzle, said fuelsupplying means comprising a fuel metering pump, means supporting saidpump for movement in response to pressure, said fuel metering pump beingmovable in response to the pressure of fuel in the discharge side ofsaid pump for rendering said pump inoperative to supply fuel to saidnozzle below a predetermined operating speed for said supplying means,and means responsive to the operation of said fuel and air supplyingmeans for increasing said discharge pressure for rendering said pumpinoperative below said predetermined operating speed for said fuel andair supplying means.

11. An oil burner system comprising a motor, fuel and air supplyingmeans driven by said motor, a mixing nozzle, conduits connecting saidmixing nozzle to said fuel and air supplying means, a centrifugallyactuated switch associated with said motor, a solenoid operated valve insaid fuel conduit, said switch and said solenoid actu ated valve beingprovided with an electrical circuit for operating said valve to open thesame when the circuit through said switch is closed, said centriiugallyactuated switch being operative for closing said circuit for actuatingsaid solenoid actuated valve when said motor is operating at apredetermined speed, said solenoid actuated valve being operative toopen said fuel supply conduit when said circuit is closed, said air"supplying means being operative at speeds below and above saidpredetermined speed for supplying a stream of secondary air past saidnozzle and said nozzle being operative for mixing the fuel and airsupplied thereto and discharging the resulting mixture into saidsecondary air stream.

12. An oil burner system comprising a motor, fuel and air pumping meansdriven by said mo, tor, a mixing nozzle for said oil burner system, saidmixing nozzle being connected to said fuel and air pumping means by fueland air con-- duits, a centrifugally actuated switch associated withsaid motor, a solenoid valve closing said fuel conduit, an electriccircuit for said motor, said switch and solenoid actuated valve beingconnected in said electrical circuit in parallel relation to said motorfor operating said valve to open the same when the circuit through saidswitch is closed, said centrifugally actuated switch being operative forclosing said circuit above a predetermined speed of operation of saidmotor, said solenoid actuated valve being operative for closing saidfuel supply conduit when said circuit is opened, and means responsive tothe closing or said fuel supply conduit for rendering said fuel pumpingmeans inoperative, said air pumping means being operative at speedsbelow and above said predetermined speed for supplying a stream ofsecondary air past said nozzle and said nozzle being operative formixing the fuel and air supplied thereto and discharging the resultingmixture into said secondary air stream.

13. An oil burner system comprising an oil and air mixing nozzle, an airpump connected with said nozzle for supplying air thereto, an oil pump,means forming a communication between said oil pump and said nozzle forsupplying oil thereto, a motor for operating said pumps, a shut-offvalve in said communication which prevents flow of oil to said nozzlewhen the valve is closed, means effective when the motor attains a predetermined speed for opening said valve, means driven with said air andoil pumps and effective above and below said predetermined speed forflowing a stream of secondary air past said nozzle, said nozzle beingconstructed and arranged to mix the oil and air supplied thereto and todis- 1?. charge such mixture into said secondary air stream, and meansfor dissipating the pressure in said communication ahead of said valvewhen said valve is closed and said motor is operating below saidpredetermined speed.

14. An oil burner system according to claim 13 wherein said pressuredissipating means comprises a by-pass around said oil pump.

15. An oil burner system according to claim 13 wherein said oil pumpcomprises two parts biased together which form said pressure dissipatingmeans, said parts being separable in response to fluid pressure in saidcommunication to relieve aid pressure when said valve-is closed.

16. An oil burner system comprising an 1 and air mixing nozzle, an airpump connected with said nozzle for supplying airtheret an oil pump,means forming a communication be tween said oil pump and said nozzle forsupplying oil thereto, a motor for operating said pumps. a shut-offvalve in said communication biased to closed position and which preventsflow oi oil to said nozzle when closed, means effective when the motorattains a predetermined speed for opening said valve and which permitssaid valve to close when the motor decelerates below its normal runningspeed, means driven with said air and oil pumps and efifective above andbeiow said predetermined speed for flowing a stream of sec ondary airpast said nozzle, said nozzle being con structed and arranged to mix theoil and air supe plied thereto and to discharge such mixture into saidsecondary air stream, and means for dissi pating the pressure in saidcommunication ahead of said valve when said valve is closed, saidshutoff valve being constructed and arranged so that the fluid pressurein said communication does not retard the closing movement thereof.

17 An oil burner system comprising an oil and air mixing nozzle, an airpump connected with said nozzle for supplying air thereto, an .oil pump,means forming a communication between said oil pump and said nozzle forsupplying oil thereto, an electric motor for operating said pumps, anelectric circuit for said motor, a shut-off valve in said communicationwhich prevents flow of oil to said nozzle when the valveis closed, meansenergized by said motor circuit when the motor attains a predeterminedspeed for opening said valve and which permits said valve to close whenthe motor circuit is opened, means driven with said air and oil pumpsand effective above and below said predetermined speed for flowing astream of secondary air past said nozzle, said nozzle being constructedand arranged tomiX the oil and air supplied thereto and to dischargesuch mixture into said secondary air Stream/and means for dissipatingthe pressure said communication ahead of said valve when said valve isclosed.

' HOWARD E. EARL.

REFERENCES CITED The iollowing references are of record in the file ofthis patent:

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